Originally Posted by ykobayashi

I don’t have any tips for you but all I can say is immobilizer problems scare me. I can visualize my 97 c280 (also m104) getting junked because of a malfunctioning immobilizer system.

I cannot see how refueling could mess up the immobilizer. The only connection I can think of is the pneumatic lock system. The power locks are related to the immobilizer. I’ve discovered this by messing with my door lock switches and accidentally triggering the alarm. It’s all intertwined with the door lock button on the dash. And one of the vacuum actuators is on your fuel door. That is a stretch…I really cannot see how opening your fuel door and putting gas in triggers the immobilizer.

Is there some kind of switch that checks to see if somebody siphons your gas?

Is this problem repeatable? Or has it only happened once?

Is it possible there is some kind of electronic problem in your key? Maybe turning the key is shorting out the board in the fob? Or maybe you went in your trunk and activated the security system through the antenna loop around the key? There is a way to deactivate the immobilizer this way n my c280 but I’m not sure if the 96 has this. The idea was that if you had the blade only key you need a way to deactivate the alarm before getting in the car. Of course my silly car doesn’t have a key hole on the drivers side.